By James Davey LONDON (Reuters) – German-owned discounters Aldi and Lidl, No. 2 player Sainsbury’s, and market leader Tesco were the biggest winners among British supermarkets at Christmas, according to industry data published on Wednesday. Market researcher Kantar said those performing not so well included Asda, Morrisons, Waitrose and Iceland. Marks & Spencer, which analysts believe performed well, is not included in Kantar’s monthly data set. The researcher said that over the 12 weeks to Dec. 24, Sainsbury’s sales were up 9.3% year on year, pushing up its market share to 15.8%, its highest …